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METHOi) OF INSTALLING A REsILImIT CUSHION INSERT Filad Oct. 24, 1955 2Sheets-Sheet 1 IN V EN TOR.

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METHOD OF INSTALLING A RESILIENT CUSHION INSERT Filed Oct. 24, 1955 2Sheets-Sheet 2 F Fa F/ mlwww United States METHOD OF INSTALLING ARESILIENT CUSHION INSERT Fred L. Haushalter, Pontiac, Mich.

Application October 24, 1955, Serial No. 542,354

3 Claims. (Cl. 29-451) The invention relates to a method of installingresilient cushion inserts within a recess in a rigid member which recessis less in width than the unstressed resilient member. This applicationforms a continuationin-part of my pending applications for patentsSerial No. 419,225, filed March 29, 1954, now Patent No. 2,795,- 036 andSerial No. 425,517 filed April 26, 1954, now Patent No. 2,795,037, eachbeing on a vibration damper and including a cushion insert ofrubber-like material. The invention consists in the method of installingthe insert and pretensioning the same. With the foregoing in view, theinvention consists in the construction and the method of forming thesame as hereinafter .set forth.

In the accompanying drawings:

7 Figure 1 is a cross section on line 11 of Figure 4 through a recessedrigid body having a prestressed rubber-like insert therein;

Figure 2 is a cross section illustrating one method of installing theinsert within the rigid body and simultaneously pretensioning the same;I

Figure 3 is a similar view showing a slightly modified construction;

Figure 4 is an elevation partly in section of a-track bar for acaterpillar type tractor having a resilient cushion insert therein; I

Figure 5 is a bottom plan view of one of the shoes of a modified type ofcaterpillar tractor having a pair of cushion inserts therein;

Figure 6 is a cross section on line 6-6 of FigureS.

Figure 7 is a section similar to Figure 1 showing a modifiedconstruction. 7

The subject matter of each of my prior applications for patents abovereferred to, is a vibration damper which includes a pretensioned annularinsert of rubber-like material. The pretensioning is obtained by formingthe insert of greater cross-sectional width than that of the annularrecess in which it is installed and then stretching said insert toreduce the width of the cross section thereof during installation. Thewalls of the recess are formed by relatively movable generally coaxialmembers which relative movements are cushioned by said insert. Thereare, however, many other structures in which it is desirable to placewithin a recessed rigid body a pretensioned resilient insert. Forinstance track shoes of caterpillar type tractors have been formed withinserts of rubber-lilns material which reduce wear when traveling overhard pavements. It has beenthe practice in forming these shoes tovulcanize the rubber to the metal portion of the shoe which adds aconsiderable item to the cost of manufacture. Also shrinkage of theinsert by cooling after vulcanization is detrimental. With my method ofinstalling the insert, vulcanization is unnecessary and instead ofcontraction of the installed insert, it is in-effect under compressionwhich increases its eificiency. There are-'other-structures havingrubber-like inserts .inwhich it would be advantageous to avoid thenecessity of vulcanization, and which would at the same time securelyretain the insert from displacement.

The essential feature of my construction isthat the resilient insert isformed of greater cross-sectional width than that of the recess in therigid body in which it is installed. This involves the problem ofassembly. If the rubberdike body were forced into the recess by pressureagainst its outer end, the frictional resistance developed between therubber and the metal by expansion stresses within the former would bedifficult to overcome and would probably result in injury to the insert.I have overcome this difficulty by stretching the insert in a directiontransverse to its cross-sectional width, thereby reducing the width andthe friction between the same and the metal. If, however, the insert isplaced in a. recess which i s closed on all sides other than itsentrance, the problem is how to effect this stretching. This I haveaccomplished by placing a thin member formed of rigid material, such asmetal, within the body of the insert to extend from near the entranceend thereof to beyond the rear end. Pressure applied to the rear end ofthis rigid member will be transmitted to the forward end of the insertto force it into the recess, and frictional resistance by the walls ofthe recess will only have the effect of stretching the insert andthereby reducing its cross-sectional width. 7

As .shown in Figure 1 the rigid member A is of U- shaped cross sectionto form a channel-shaped recess within which is placed the insertelongated resilient B. Figure 2 shows the insert B as originally ofgreater cross-sectional width than the recess within the member A. Suchinsert B is also provided centrally with a longitudinally extending thinslot B' which extends in depth from its rear edge to within a shortdistance of its forward edge which as indicated at B is rounded. C is athin plate-like rigid member within the slot B extending rearward beyondthe same. Thus pressure applied on the outer end of the member C will,as above stated, force the insert edgewise into the recess and at thesame time stretch it so as to reduce its width. Figure 3 shows amodified construction in which the insert D has a pair of spaced slotsD, -D extending therein on opposite sides of the center thereof. Therigid member E has corresponding spaced thin plate-like rigid portions Eand E for engaging said slots. This will afford a more stableconstruction than that illustrated in Figure 2 for forcing the insertinto the recess. With both constructions the insert will be stretchedsufficiently to reduce its width to that of the recess and aftercomplete insertion the rigid members C and E may be withdrawn, whereuponcontraction of the stretched member will close the slots B and D, D

However, the contraction in stretched length required for closing theslots is less than the total stretching during insertion so that theinsert is still under stress tending to expand the same transversely.This will insure sufiicient frictional contact between the insert andthe walls of the recess to retain the former without the necessity ofvulcanization. As the pressure of the member E is applied to the centralportion of the insert and as the side portions thereof are retarded byfriction with the walls of the recess, this central portion will beadvanced to a greater degree than the side portions. This would resultin concaving the outer end of the insert and to avoid such result thecentral portion is originally extended rearward beyond the sideportions. Thus the portion of the insert between the slots D, D projectsrearward at D beyond the portions outside of said slots. Duringinsertion of the member D the friction of the spaced {portions E and Eof the member E on the central portion of the insert which istherebetween will draw this projecting portion D inward so that its rearend will be more nearly in line with the side portions.

Figure 4 is a sectional elevation of one of the transversely extendingtrack bars of a caterpillar type tractor and of which Figure l is across section. It will be noted that the bar A is of inverted U-shapecross section throughout its length but that the vertical depth in thecentral portion A of the bar is greater than in the end portions A and Athereof. The insert B also extends the full length of the bar and isfashioned to correspond in depth to the portions A, A and A thereof. Itis also provided with one or more longitudinally extending slots such asB, Figure 2, or D', D Figure 3 which slots extend in depth from thelower edge of the insert to within a short distance from the upper edgethereof. Rigid members such as C or E engage these slots and form themeans for prestretchiug the insert and engaging the same with the bar asabove described. When these rigid members are withdrawn the insert willstill be retained by the resilient stresses remaining there- Theconstruction illustrated in Figures 5 and 6 is of a track shoe F havingspaced projecting lugs F, F and F at one edge thereof and spaced lugs Fand F projecting from the opposite edge for engaging the spaces betweenthe aforesaid lugs in the next adjacent shoe and pivotally connectedthereto. As heretofore constructed,

these shoes are formed with triangular recesses in their under-faces forreceiving rubber inserts vulcanized to the metal of the shoe. I havechanged the construction by forming channel recesses each with parallelside walls and adjacent respectively with opposite oblique sides of thetriangle extending to a common apex. These channels can either be formedin the original casting or, as shown, by spaced bars G and G welded tothe casting. (lushion inserts H of resilient rubber-like material areinserted edgewise within said channels by the method above described andby the use of thin. rigid members which are in slots extending the fulllength of said members. Thus, the resilient stresses within the inserttending to expand it transversely will so increase the friction with thewalls of the recess as to retain the insert without the necessity ofvulcanization. Similar prestretched inserts may be placed in recesses inthe top of the shoe, as indicated at I and I.

For some uses itmay be desirable to provide the walls of the recess withone or more inwardly projecting lugs which will be embedded in theinsert and will assist in retaining the same. Such a construction isshown in Figure 7 in which the member A has portions J and 1' thereofstruck inward from opposite walls to form said lugs. The insert B may beinstalled by the method previously described during which the lugs J andI will become embedded in the rubber.

What I claim as my invention is:

l. The method of anchoring without vulcanization an elongated resilientinsert edgewise within a channelshaped recess in a rigid body,comprising the steps of forming an elongated insert similar inconfiguration to but of greater cross sectional width than that of saidchannel-shaped recess with a longitudinally extending central portionthereof projecting rearwardly beyond the rear edge of said insert andwith parallel'longitudinally extending thin slots respectively uponopposite sides of said longitudinally extending rearwardly projectingcentral portion and extending in depth from the rear edge of said insertto within a short distance of its forward edge, inserting simultaneouslyinto said spaced slots a pair of correspondingly spaced correspondinglythin rigid portions of a pressure exerting member so that saidrearwardly projecting central portion will be received between saidspaced thin rigid portions, moving the assembled pressure member andinsert toward said rigid body to place the forward edge of said insertlengthwise against the mouth of said channel-shaped recess, applying aforward force to the pressure member to stretch the side portions ofsaid insert disposed betweensaid pressure member and the walls of saidrecess lengthwise of said spaced thin rigid portions to reduce the widthof said side portions and simultaneously move said insert edgewise intosaid recess and move the rearwardly projecting central portion into saidrecess between the spaced slots therein while confining said centralportion between said spaced rigid portions so that the rear edge of saidcentral portion will be substantially flush with the rear edge of saidinsert after full insertion thereof into said recess, and withdrawingthe thin rigid portions of said pressure member from said slots so thatthe latter will close automatically by contraction of said stretchedinsert and said insert will remain permanently in said recess undercompression between and in frictional surface to surface engagement withopposite side walls of said recess.

2. The method of anchoring without vulcanization a resilient insertwithin a recess in a rigid body, comprising the steps of forming aninsert similar in configuration to but of greater cross sectional widththan that of said recess with a longitudinally extending central portionthereof projecting rearwardly beyond the rear surface of said insert andwith parallel longitudinally extending thin slots respectively uponopposite sides of said longitudinally extending rearwardly projectingcentral portion and extending in depth from the rear surface of saidinsert to within a short distance of its forward surface, insertingsimultaneously into said spaced slots a pair of correspondingly spacedcorrespondingly thin plate-like rigid portions of a pressure exertingmember so that said rearwardly projecting central portion will bereceived between said spaced thin rigid portions, moving the assembledpressure member and insert toward said rigid body to place the forwardsurface of said insert against the mouth of said channel-shaped recess,applying forward force to the pressure member to stretch the sideportions of said insert disposed between said pressure member and thewalls of said recess lengthwise of said spaced thin rigid plate-likeportions to reduce the width. of said insert and simultaneously movesaid insert into said recess and move the rearwardly projecting centralportion into said recess between the spaced slots therein whilemaintaining unchanged the dimensions of said central portion so that therear surface of said central portion will be substantially flush withthe rear surface of said insert after full insertion into said recess,and withdrawing the thin rigid plate-like portions of said pressuremember from said slots so that the latter will close automatically bycontraction of said stretched insert and said insert will remainpermanently in said recess under compression between and in frictionalsurface to surface engagement with opposite side walls of said recess.

3. The method of anchoring without vulcanization a portion of aresilient ground engaging traction element within an outwardly openingchannel-shaped recess in a rigid portion of a track shoe for acaterpillar type tractor comprising the steps of forming an insert ofgreater width than that of said recess with side faces, said inserthaving a rearwardly projecting center portion and a thin slot on eachside of said rearwardly projecting center portion, each slot being inalignment with a side face of said projecting center portion and beingbetween said center portion and one of the said side faces of theinsert, inserting simultaneously into said slots plate-like rigidportions of a pressure exerting member so that said rearwardlyprojecting center portion will be received between said rigid portions,moving the assembled pressure member and insert toward said rigid bodyto place the forward surface of said insert against the mouth of saidchannelshaped recess, applying forward force to the pressure member tostretch the side portions only of said insert into said recess and tomove the rearwardly projecting center portion into said recess whilemaintaining unchanged the dimensions of said center portion, andwithdrawing the plate-like rigid portions of said pressure member fromsaid slots, so that the stretched portion aforesaid of said insert willremain permanently in said recess under stress between and in frictionalsurface to surface engagement with opposite side walls of said recessand so that the remaining portion of said insert will remain out-References Cited in the file of this patent side said recess to serve asa ground engaging traction 10 2,457,930

element.

UNITED STATES PATENTS Pratt June 18, 1878 Bienenstein Nov. 8, 1927 BowesOct. 8, 1929 Kraft Oct. 12, 1937 Christmas June 20, 1939- Knox Ian. 16,1940 Smith Ian. 4, 1949

